The heart is the center of a person's circulatory system. It includes a complex electro-mechanical system performing two major pumping functions. The left portions of the heart, including the left atrium (LA) and the left ventricle (LV), draw oxygenated blood from the lungs and pump it to the organs of the body to provide the organs with their metabolic needs for oxygen. The right portions of the heart, including the right atrium (RA) and the right ventricle (RV), draw deoxygenated blood from the organs and pump it into the lungs where the blood gets oxygenated. These mechanical pumping functions are accomplished by contractions of the myocardium (heart muscles). In a heart having a normal electrical system, the sinoatrial node, the heart's natural pacemaker, generates electrical signals, called action potentials, at a rate responsive to the body's metabolic need. The action potentials propagate through an electrical conduction system to various regions of the heart to excite myocardial tissues in these regions. Coordinated delays in the propagations of the action potentials in a normal electrical conduction system cause the various regions of the heart to contract in synchrony such that the pumping functions are performed efficiently. When the electrical system functions abnormally, the heart may contract in a rate that is abnormally slow or abnormally fast, or that contractions at one or more cardiac regions become chaotic and asynchronized. Such conditions are known as cardiac arrhythmias. Cardiac arrhythmias result in diminished blood flow in the circulatory system and hence insufficient oxygen supply to meet the body's metabolic needs.
Arrhythmias are treated by therapies including, but not being limited to, various types of pacing, cardioversion, and defibrillation therapies delivered by implantable CRM devices. To deliver the right type of therapy with adequate timing, one or more biopotential signals, called electrograms, are sensed to indicate of a cardiac rhythm, including the type of arrhythmia when the cardiac rhythm becomes abnormal. An intracardiac electrogram is sensed with at least one electrode placed in or on the heart. Depending on the location of the electrode, the intracardiac electrogram indicates localized electrical activities of one particular cardiac region. Under certain circumstances, the localized electrical activities may indicate an ongoing arrhythmia but not the origin of that arrhythmia. Additionally, reliability of intracardiac electrogram-based arrhythmia detection may be compromised by noise or poor electrical connections between the heart and the sensing circuit, which occur due to bodily movements and environmental factors.
To enhance the effectiveness of therapy for cardiac arrhythmias, there is a need for enhancement of intracardiac electrogram-based arrhythmia detections.